<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>盒子模型</title>
	</head>
	<style>
		#div1{
			background-color:skyblue;
			border: 9px  ;
			width: 400px;
			height: 400px;
			padding-right: 100px;
		}
		#div2{
			background-color: orchid;
			width: 350px;
			height: 350px;
			border: 9px;
			margin: 0 auto;
		}
		#div3{
			background-color: gold;
			width: 200px;
			height: 200px;
			padding-left: 20px;
			margin: 0 auto;
		}
	</style>
	<body>
		<div id="div1">
			<div id="div2"><div id="div3"></div>
			</div>
			</div>
	</body>
</html>
